Even if you dont like CT, its useful. It puts your plane in trim for whatever speed you are travelling, to put it at its most basic. Turn it on, watch your trim indicators move around, when they stabilize turn it back off. You are now pretty darn close to a neutral trim and can hold speed better. Until you slow back down, then you need to trim the plane for slower speeds.
Combat Trim is not something I leave on all the time, it is useful on a situational basis however. Its a tool like any other. Learn what it does, use what you want to of it. Thats what tools are for.